Updated the Swift installation steps for Grizzly

These changes were made following an installation of Swift and Keystone
on Ubuntu 12.04.2 using Ubuntu's Cloud Archive packages.

 * Some minor changes to "screen" blocks to introduce a space between
   "#" and the command to run.

 * Install python-keystoneclient rather than python-keystone-auth-token
   (the auth_token module moved during grizzly).

 * Install python-webob on the proxy server. It's required by
   auth_token.

 * Add instructions for creating the 'signing_dir' on the proxy server.

 * Use 'service' rather that 'swift-init' to start the various services.
   On reboot upstart will start the services anyway. Best to be
   consistent.

 * Removed instructions to create account-server.conf,
   container-server.conf and object-server.conf. These files come as
   part of the Ubuntu packages and work out of the box.

 * Moved the instructions on starting the object storage services into a
   new section following the installation of the ring files. They made
   no sense where they were as the services wouldn't start sucessfully
   until the ring files are in place.

 * Tidied up the sample proxy-server.conf.txt by removing unused
   settings and annotating the rest.

 * Added instructions to create the swift recon cache dir on each
   storage node

Change-Id: I8001849b0a492060d51f38be024b1acee569585b
Merge "Updated the Swift installation steps for Grizzly"